Exhibit 16-4
In a laboratory experiment, data were gathered on the life span (Y in months) of 33 rats, units of daily protein intake (X 1 ), and whether or not agent X 2 (a proposed life extending agent) was added to the rats diet (X 2 = 0 if agent X 2 was not added, and X 2 = 1 if agent was added.) From the results of the experiment, the following regression model was developed. Also provided are SSR = 60 and SST = 180.
-Refer to Exhibit 16-4. The model
A)is significant
B)is not significant
C)Not enough information is provided to answer this question.
D)None of these alternatives is correct.

Question

Exhibit 16-4
In a laboratory experiment, data were gathered on the life span (Y in months) of 33 rats, units of daily protein intake (X 1 ), and whether or not agent X 2 (a proposed life extending agent) was added to the rats diet (X 2 = 0 if agent X 2 was not added, and X 2 = 1 if agent was added.) From the results of the experiment, the following regression model was developed.  Also provided are SSR = 60 and SST = 180.
-Refer to Exhibit 16-4. The model
A)is significant 
B)is not significant 
C)Not enough information is provided to answer this question. 
D)None of these alternatives is correct.

Quizplus · Accepted Answer

To determine if the model is significant, we need to perform an F-test. However, the output for the model is not provided, so we cannot calculate the F-test statistic. Instead, we can look at the R-squared value, which tells us the proportion of variation in the dependent variable (life span) that is explained by the independent variables (protein intake and whether or not the life extending agent was added).
R-squared = SSR/SST = 60/180 = 1/3 = 0.33
Since the R-squared value is not close to 0 (indicating that the model explains some of the variation in the dependent variable), the model is likely significant. Therefore, the best answer is A, the model is significant.

Exhibit 16-4 In a Laboratory Experiment, Data Were Gathered on the Life